'March 31, 1964
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L. B. BQRST
3,127,321
. NUCLEAR REAoToR Foa A RAILWAY VEHICLE
Filed April 7, 1955
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March 3l, 1964
L.. B. BoRs'r
3,127,321
NUCLEAR REAcToR FoR -A RAILWAY VEHICLE
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LYLE B. BORST
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March 31, 1964
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L. B. BORST
NUCLEAR REACTOR FOR A RAILWAY VEHICLE
Filed April 7, 1955
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INVENTOR.
LYLE B. BORST
BY
ATTORNEY
United States Patent O ” ice
1
3,127,321
NUCLEAR REACTOR FOR A RAILWAY VEHICLE
Lyle B. Borst, Qssining, N.Y., assigner to
University of Utah, Salt Lake City, Utah
Filed Apr. 7, 1955, Ser. No. 499,867 '
2 Claims. (Cl. 176-38)
My invention relates in general to the construction and
operation of nuclear reactors and more particularly, to
a homogeneous type nuclear reactor especially designed
and particularly useful for a mobile power plant.
3,127,3Zl
Patented Mar. 31, 1964
2
driving potential of the dissociated water vapor, vapor,
and gaseous fission products which pass 0E from the
liquid fuel solution, to drive a turbine which in turn drives
a pump for the circulation of the fuel solution within the
fuel chamber, thus increasing the heat transfer effective
ness of the fuel solution.
A further feature is in the provision of means for super
heating the power plant working ñuid by passing the va
por generated in cooling relation with the primary shield
heated by the gamma radiations of the reactor. This ar
rangement gives the steam a measure of superheat, thus
The design of any power reactor requires that large
guaranteeing that the steam is dry and also reducing the
external heat loss of the primary shield.
the necessity of obtaining good heat transfer conditions
The various features of novelty which characterize
often dictates the arrangement of the reactor. From a 15 the invention are pointed out with particularity in the
nuclear standpoint the reactor core is desirably arranged
claimsv annexed to and forming a part of this specifica
amounts of heat be removed from the reactor core and
in a geometric pattern so as to have the smallest ratio of
tion. For a better understanding of the invention, its
core bounding surface to volume in order to minimize
operating advantages and specific objects attained by its
neutron escape. Such considerations have caused some of
use, reference should be had to the accompanying draw
the prior reactor cores to be constructed in the general 20 ings and descriptive matter in which I have illustrated and
form of a sphere. Other shapes that have been used are
described a preferred embodiment of the invention.
righ circular cylinders having a length to diameter ratio
greater than one and polygons having a length greater
than its major cross axis.
Of the drawings:
FIG. l is a sectional elevation through a nuclear reactor
embodying the invention;
Almost all of these reactors have been designed for 25
FIG. 2 is a transverse section taken on the line 2-2
low power output and have utilized solid fuel. Solid fuel
of FIG. 1;
or heterogeneous reactors by their construction limitations
FIG. 3 is an isometric drawing of the exterior of the
can not have a high efficiency of neutron liberation, be
reactor with the shell removed; and
cause the fuel cladding material and the coolant heat
FIG. 4 is a view of the reactor as mounted in a loco
transfer surfaces interfere with the eñîcient transfer of 30 motive.
The nuclear reactor illustrated utilizes a homogeneous
neutrons for further ñssion. In contrast, homogeneous
solution of uranium sulphate in light water, with the re
type reactors, where the Íissionable material is in solution,
have a high neutron efficiency and are more readily adapt
actor being cooled by heating light water under forced
ed to geometries which deviate considerably from the
circulation at a vaporizing temperature. The reactor has
35 a fuel chamber 10 formed by a cylindrical pressure wall
above mentioned sphere.
Mobile reactors have the overriding consideration that
12, a pair of spaced circular tube sheets 14 and 16 ar
they must be relatively small in size to fit into the avail
ranged to close the ends thereof, and a multiplicity of
small diameter coolant tubes 18 extending between and
able space, .while releasing large amounts of heat, i.e.,
opening through said tube sheets. Disposed at opposite
capacity to operate at high power densities. In units of
this type the removal of heat is a major criteria for de 40 ends of the cylindrically shaped fuel chamber are a cylin
drically shaped fuel chamber are a cylindrical coolant
termining a design.` Factors aifecting the heat transfer
inlet chamber 20 and a cylindrical coolant outlet chamber
such as uniform removal of heat throughout the core,
22. Directly above the fuel chamber 10 and in com
characteristics of the heat transfer or coolant ñuid, and
munication with it, is a catalytic recombiner chamber 24.
structural limitations, are more influential design factors
than the nuclear requirements.
Adjacent the recombiner chamber 24 is a separate ex
45
The nuclear reactor of my invention is particularly char- v ternal steam separator 26 which has a riser 28 in com
acterized by the construction of the reactor core or fuel
chamber in the shape of a right circular cylinder having
munication with the outlet chamber 22, a downcorner
Sil connected to the coolant inlet chamber itl, and a va
por outlet line 32. Subjacent the cylindrical fuel cham
an axial length to diameter ratio of less than 0.75, and
with the circular end portions of the cylinder serving as 50 ber is a coolant pump 34 arranged to force-circulate the
coolant fluid from the outlet chamber 22 via the suction
tube sheets for a multiplicity of small diameter, longitudi
nally disposed, spaced cooling tubes which pass through
the core or fuel chamber. Within the cylinder and around
the tubes there is a water solution of uranium sulphate
line 3d to the coolant inlet chamber Ztl via line 3S. Dis
posed adjacent to but spaced from the outer sides of inlet
and outlet chambers are two parallel steam superheater
55 sections 4@ and 42, each being formed in a sinuous tube
bank in thermal contact with a vertical end wall 44 of
Another feature of my invention is the provision of inlet
the primary shielding structure 45, formed of steel, e.g.,
and outlet chambers on the outer side of each tube sheet
8” thick. The shielding 45' is completed by a U-shaped
which when filled with water act as reflectors.
or the like.
side wall 47 and and roof 49 connected to the end walls
A further feature of my invention is that the water
which is used for a reñector, can be the reactor coolant 60 44, and the entire reactor is disposed within the shielding.
Within the fuel chamber lil are a pair 0f spaced ver
fluid and may be either boiled to generate steam or may
tically arranged fuel circulation bafiies 46 which assist
simply be heated for a further heat transfer step in an
auxiliary heat exchanger where the coolant fluid transfers
in guiding the circulation of the liquid fuel. Arranged
to take suction from the liquid fuel contained between the
heat to a vaporizable fluid for vapor generation.
A still further feature of my invention is the provision 65 baffles 46 is a fuel circulating pump dit. rîhis pump is
driven by a turbine 50 which receives its driving energy
of a catalytic recombiner in which the dissociated wa
from the dissociated water vapor, vapor, and ñssion gases
ter vapor from the fuel solution is externally recombined
which rise off of the liquid fuel surface indicated at 52
and then condensed by the vapor generator feed water
and pass into the recombiner chamber 24. Immediate
in indirect heat exchange so as to constitute in effect a
continuously refluxing condenser.
Another feature of my invention is in the use of the
70 ly upon entering the chamber 24 the dissociated water
vapor first passes through a body of catalyst 51 which
3,127,321
4
3
may be activated platinum, where the hydrogen and oxy
secondary shield 66.
gen is recombined in an exothermic process.
carbon which is high in hydrogen content.
The re
Such a material would be a hydro
The steam from the reactor flows from the superheated
leased heat superheats the ñssion gases and water Vapor.
The condensible vapor is then partly condensed by a con
denser coil 53 in the upper end of the chamber 24. The
cooling fluid for the condenser coil is the vapor gen
erator feed water which enters the recombiner chamber
steam outlet 43 into a steam turbine '76 which drives con
ventional railway electrical generating equipment and
which in turn drives the electric traction motors of a well
known type on the carriages 74.
By way of example, and not of limitation, one loco
by the line 55 and is discharged by the line 54 into the
motive reactor of the character described was designed
reactor inlet coolant chamber 20. The condensed water
is carried out of the recombiner through the line S6 and 10 with a fuel chamber dimension of 3 feet diameter and
10 inches in length, and containing 10,000 1A; inch tubes.
returned to the fuel chamber l0 to maintain the liquid
Table I shows the designed operating conditions of the
locomotive.
fuel level therein. Disposed within the fuel chamber 10
are emergency cooling heat transfer tubes 58 having their
opposite ends connected to inlet and outlet headers 60
and 62.
On the occurrence of a predetermined condi
TABLE I
15
tion, an emergency cooling fluid can be forced through
the cooling loop 58 from an external source (not shown)
in order to remove the reactor decay heat.
The reactor is controlled to maintain a predetermined
Operating Conditions
Reactor heat generating (continuous) ___ 30,000 kw.
team pressure (saturated) _________ __ 250 p.s.i.
fuel temperature, thus changes in this temperature would 20
Reflector temp ____________________ __ 405° F.
Fuel solution temp ________________ __ 460° F.
change the power output. Control rods 64 are adapted
to be reciprocably moved according to the proper con
Turbine exhaust pressure ___________ __ 6" Hg.
Steam ñow _______________________ _. 120,000- lb./hr.
trol signal by any of the presently known control systems
Turbine power (continuous) ________ __ 8,000 I-LP.
for reactors.
Cycle efficiency ___________________ __ 20%.
In the operation of this reactor control rods 64 are 25
The reactor characteristics of the locomotive type is
moved until the reactor goes critical. The reactor coolant
shown in Table II below.
circulating pump 34 is started so that the light water
TABLE lII
coolant is circulated from the inlet chamber 20 through
the tubes llS into the outlet chamber 22 and then back
Nuclear Operating Data
to the pump, until a steaming condition is reached. Then 30
(a) Homogeneous solution ____________ _. UO2SO4.
a control valve (not shown) on the outlet 43 of the
superheater 40, 42 would be opened. The steam which
(b) H/U255 atomic ratio ______________ __ 700.
is generated as it passes through the reactor coolant tubes
(c) H20/Um weight ratio ____________ __ 27.
(d) U235 ___________________________ _. 9.0 Vkg.
18 passes up the steam riser tube 28 into the steam and
Water separator 26. The separated water passes down 35 (e) UO2SO4 weight __________________ _. 13.9 kg.
the downcomer into the inlet chamber 20 and the sep
arated steam passing into the superheater sections 40 and
(f) H2O required ___________________ __ 243 kg.
(g) Assumed densityl of solution _______ __ 1.0 g./cm.3.
(h) Solution circulation rate ___________ __ 500 g.p.m.
42. As the steam passes through the superheater, which
(i) Reflector circulation rate __________ _- 2000 gpm.
is in contact with the primary shielding 44, the steam
picks up a small degree of superheat in cooling the shield 40 (j) Solution pressure _________________ __ 650 p.s.i.g.
(k) Reflector pressure ________________ _. 250 p.s.i.g.
end walls 44, which in turn receive heat from the gamma
(l) Power generated _________________ _. 30,000 kw.
radiations from the reactor. Thus there is generated
(m) Excess reactivity ________________ _- 10%.
steam for the prime mover in a homogeneous type boiling
(n) H2O decomposition rate __________ __ 32 g./sec.
reactor.
In FIG. 4 there is shown a speciiic application of my 45
(o) Solution temperature ______________ _. 460° F.
mobile reactor as used as a power source for a railway
(p) Reflector temperature _____________ _. 405 ° F.
locomotive. The reactor, which is Within the primary
shield 45, is centrally located within a large shielding
The inlet and outlet chambers 20, 22 by their construction
chamber formed by the secondary shield 66.
and arrangement are especially adapted to act as a neu
The re
tron reflector, and by virtue of the described geometric
actor is arranged therein with the fuel chamber major 50 arrangement of the fuel chamber they cover a large por
axis in a plane coincidental with the longitudinal axis of
tion of the surfaces of the fuel chamber, thus contribut
the locomotive underframe 68, thus providing the maxi
ing to the neutron conservation of the reactor.
mum shielding distance between the primary shield 45
The geometric configuration of the fuel chamber, being
andthe secondary shield 66. The reactor and the primary
a right circular cylinder with a length to diameter ratio
shield are supported on the pedestals 70 which in turn 55 of considerably less than 0.75, makes possible the use of
rest on the secondary shield 66. The secondary shield,
short longitudinally disposed cooling tubes so as to al
also being of 8” thick steel, constitutes a center panel
low operation of the reactor at a high power density with
of a heavy duty bridge truss 72 which allows the weight
the boiling cooling Water having a short flow path, thus
of the reactor to be transmitted to and carried by the
holding the volume of steam generated in each tube dur
traction assembly 74. The secondary shield is also ar 60 ing its traversing of the fuel chamber to a minimum. This
ranged to utilize to a maximum extent the allowable
allows the boiling Water to maintain its high heat transfer
effectiveness without the large reactivity change which
width of the railway car underframe, the outer sides of
the shield being in substantial vertical alignment with
would occur with large amounts of steam in each tube.
the side edges of the underframe. In one such case, the
The integral turbine and pump arrangement in the
outer dimensions of the secondary shield were 10 feet 65 fuel chamber of the reactor provides for a forced circula
wide, 15 feet long and l5 feet high. The space between
tion of the liquid fuel by utilizing the heretofore wasted
the inner primary shield and the outer secondary shield
energy of the dissociated vapor and fission gases as they
is filled with a shielding material, which is approximately
travel to the catalytic recombiner and results in highly
one-half steel and one~half hydrogenous material of about
improved heat transfer conditions within the fuel cham~
unit density, which gives the shield a total weight of ap 70 ber. The condenser part of the recombiner operates as
an economizer for heating the feed water and thus in
proximately 400,000 pounds. Under emergency condi
creases the efliciency of the working cycle.
tions, such as wrecks, the presence of a shielding mate
rial of high viscosity between the inner and the outer
While in accordance with the provisions of the statutes
shield structures is advantageous in effecting the decel
I have illustrated and described herein the best form of
eration of _the internal or primary shield 45 within the 75 the invention now known to me, those skilled in the art
3,127,321
5
6
will understand that changes may be made in the form of
side edges of said underframe, a second ñuid-tight radia
tion shield vessel closely surrounding said source inter
nally of and spaced from said first named shield vessel, a
vapor superheater in heat transfer relationship to the in
terior surface of said second radiation shield, means for
passing vapor through said superheater to remove heat
from said shield surface and efîect the superheating of said
vapor, a high viscosity ñuid ñlling the space between the
shield vessels having the ability to decelerate any move
the apparatus disclosed without departing from the spirit
of the invention covered by the claims, and that certain
features of the invention may sometimes be used to ad
vantage without a corresponding use of other features.
I claim:
1. A radiation shielding arrangement for a high energy
nuclear radiation source in a railway vehicle compris
ing a railcar underframe, said radiation source in the form
of a right circular cylinder of a length to diameter ratio 10 ment of said internal vessel, and a hydrogenous mate
of less than one and arranged with its major axis in a
rial placed in said high viscosity liquid to increase the
plane coincidental with the longitudinal axis of said under
shielding eiîect of the liquid.
frame, a radiation shield vessel enveloping said source and
References Cited in the ñle of this patent
mounted on said underframe with the vertical external
UNITED STATES PATENTS
sides of said shield being in vertical alignment with the 15
side edges of said underframe, a second fluid-tight radia
Fermi et al _____________ __ May 17, 1955
2,708,656
tion shield vessel closely surrounding said source inter
OTHER REFERENCES
nally of and spaced from said first named shield vessel, a
high viscosity ñuid iilling the space between the shield
vessels having the ability to decelerate any movement of
said internal vessel, and a hydrogenous material placed
ABCD-3287, February 7, 1952, 17 pages, Technical In
formation Service, Oak Ridge, Tenn.
in said high viscosity liquid to increase the shielding effect
of the liquid.
U.S. Atomic Energy Commission AECD~3065, Septem
“Nucleonics,” Vol. 12, No. 3, pp. 78 and 80. March
1954.
2. A radiation shielding arrangement for a high energy
ber 19, 1945, pp. 1-28.
Applied Atomic Power by E. S. C. Smith et al., Prentice
nuclear radiation source in a railway vehicle comprising 25
a railcar underframe, said radiation source in the form
Hall, N.Y., 1946, pp. 160-169.
Business Opportunities in Atomic Energy. Proceedings
of a right circular cylinder of a length to diameter ratio
of a meeting March 15 and 1'6, 1954, Biltmore Hotel, New
of less than one and arranged with its major axis in a
plane coincidental with the longitudinal axis of said under
York, N.Y., pub. by Atomic Industrial Forum, Inc., 260
frame, a radiation shield vessel enveloping said source and 30 Madison Ave., New York 1‘6, N.Y., © May 1954. (Edi
tors of report: Oliver Townsend, Edwin Wiggins, pp. C2
mounted on said underframe with the vertical external
sides of said shield being in vertical alignment with the
to C15.)